Technical Report : EQUINE ADENITIS

This is an acute disease which affects horses of all ages, caused by Streptococcus equi. It produces inflammation of the upper respiratory tract and abscesses of the retropharyngeal and/or mandibular lymph nodes. More frequent clinical symptoms are fever, serous nasal secretion which then turns into mucopurulent and pharyngitis which can obstruct swallowing.

The recommended treatment consists on an antibiotic therapy, Penicillin and it´s derivates. Penicillin and Ampicillin are beta-lactam antibiotics, which act on the bacteria wall.

The infected animals were separated into two groups to observe the response to AMPICILLIN COMPLEX and SODIUM PENICILLIN which was used as control.

Materials and Methods
Animals: six crossbreed horses of 400 kg body weight with incipient adenitis were used. They were separated into two groups of three animals each. Group A was treated with 10.000.000UI of Pure Penillin (Sodium Penicillin G) every 8 hs, while Group B received 5 g of Complex Ampicillin (Sodium and benzathine Ampicillin) every 12 hr. Both treatments lasted 10 days.


  • Rectal temperature: There was only one animal with fever in each group at the moment of diagnosis (39,1ºC /Group A; 40º/Group B) By day 5 of treatment, the horse from group A no longer had fever: while the horse from group B still had 39.4º C. By the tenth day of treatment, none of the animals of either group had rectal temperature higher than 37.5ºC.
  • Nasal discharge: At the moment of carrying out the diagnosis only two animals from Group A and one of group B had nasal discharge. On the fifth day of treatment, all horses had mucopurulent nasal discharge.
  • Cough reflex: At the beginning of the disease, only one horse from Group A and three from Group B had positive reflex. After 5 days of treatment, no horse of Group A had positive reflex, and from Group B, only one had no positive reflex. At day ten of the beginning of the therapy, only two horses from Group B showed signs of positive cough reflex.
  • Lymph nodes: (mandibular and retropharyngeal lymph nodes) Only one horse from Group B did not show inflamed nodes at the moment they were diagnosed with Adenitis, all the other had inflamed nodes. The inflammation was also noticeable on the floor of the guttural pouch (photo 1B) A horse from Group A also had a fistula which drained into the guttural pouch (Photo 1A)

PHOTO 1A shows the empyema due to fistulisation of the retropharyngeal node into guttural pouch, and PHOTO 1B shows the bulge of the node into the guttural pouch.

After 5 days of treatment, all the horses had their lymph nodes inflamed, and one of it had a mandibular node fistula (Photo 2).

Photo 2: Fistula of left mandibular node (arrow) at the fifth day of treatment.

After 10 days of treatment all the horses from both groups had only slightly inflamed nodes, and this inflammation only slightly deforms the guttural pouch (Photo 3B).
Photo 3A shows the chondroid (arrow) after purulent exudation and in 3B we can see the slight protrusion into the guttural pouch.

Animals treated with Pure Penicillin (Group A) showed a negative cough reflex and normal temperature at day fife of treatment while nasal discharge was still present and lymph nodes were still inflamed. At day 10 of treatment, only two horses continued with serous discharge while the other three horses from the group still had slighty inflamed lymph nodes, but body temperature was normal and cough reflex was absent. The horse with the fistula into the guttural pouch was treated by washing out the pouch using a solution of iodinepovidone 3% during three days and the chondroid was removed by endoscopic via.

Two animals treated with Ampicillin complex had positive cough reflex , and the horse which had begun with 40ºC (rectal temperature) still continued with fever. Every animal of this group had nasal discharge and inflamed lymph nodes. After 10 days of treatment, one animal had mucopurulent nasal discharge and two positive cough reflex. No animal had fever, but all of them still had slightly inflamed lymph nodes.

To conclude, horses treated with Ampicillin complex (Group B) had a good response to treatment, although less rapid than the group treated with Pure Penicillin, which is the chosen antibiotic for this illness. 10 days after beginning treatment (20 days from onset of the disease) all animals from both groups had recovered. The administration of Ampicillin Complex every 12 hrs. makes the treatment easier and cheaper. It is important to point out, that the auto-vaccine (highly recommended for this illness) was not given this time, so as not to mask the action of antibiotic.


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